JP2724483B2 - Method for bonding nitrile group-containing highly saturated polymer rubber to polyester fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for bonding a nitrile group-containing highly saturated polymer rubber to polyester fibers.

(Prior art) Natural rubber latex and synthetic rubber latex have been conventionally used in various fields, but one of them is as an adhesive between rubber and reinforcing organic fiber such as polyester fiber or polyamide fiber. is there. When the rubber is a conventional rubber such as natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber (NBR),
An adhesive composed of styrene-butadiene-vinylpyridine copolymer rubber latex (VP latex) and resorcin-formaldehyde resin is used, and sufficient adhesive strength is obtained.

However, hydrogen value NBR, which was developed as an automobile exhaust gas countermeasure rubber, has an extremely low content of unsaturated bonds in the molecular chain, and in the adhesive using VP latex in the previous term, hydrogenated NBR and reinforcing organic fiber were used. Adhesive strength is insufficient. The present inventors have proposed the use of hydrogenated NBR latex as one of the improvement methods (Japanese Patent Application No. 62-80741).
In this method, an adhesive composed of hydrogenated NBR latex, which is obtained by hydrogenating emulsion-polymerized NBR and then latexed by a phase inversion method, and a resorcinol-formaldehyde resin is used, but the adhesive is applied to polyamide fibers or polyester fibers. After being dried and heat-treated under conventional conditions and then vulcanized and bonded to hydrogenated NBR, the initial adhesive strength at room temperature is satisfactory for polyamide fibers, but not for polyester fibers. Need further improvement.

(Problems to be solved by the invention) The inventors of the present invention have conducted intensive studies to solve the above-mentioned shortcomings,
When heat treatment is performed after attaching an adhesive composed of resorcin-formaldehyde-latex resin to polyester fiber, unlike conventional heat treatment of natural rubber etc. and polyester fiber, the heat treatment temperature specifically affects the initial adhesive strength I found something.

That is, when vulcanizing and bonding conventional natural rubber or styrene-butadiene copolymer rubber or the like, a vinylpyridine-based polymer latex and a polyester fiber treated with an adhesive composed of a resorcin-formaldehyde resin, the polyester fiber is bonded to the adhesive. After applying and drying, usually 230
It is used after being heat-treated at a temperature of ~ 240 ° C. Within this heat treatment temperature range, the higher the treatment temperature, the higher the initial adhesion, albeit slightly.

In the vulcanization adhesion between the nitrile group-containing highly saturated polymer rubber and the polyester fiber, the present inventors apply an adhesive composed of a nitrile group highly saturated polymer rubber latex and a resorcinol-formaldehyde resin to the polyester fiber, and after drying, It was surprisingly found that the heat treatment at a temperature of 240 ° C. or more significantly improved the initial adhesive strength as compared with the case where the heat treatment was performed at a temperature below this temperature, and based on this finding, the present invention was completed. Was.

Accordingly, an object of the present invention is to provide a method of bonding a nitrile group-containing highly-saturated polymerized rubber and polyester fiber which exhibits improved initial adhesive strength.

(Means for Solving the Problems) Thus, according to the present invention, when vulcanizing and bonding a nitrile group-containing highly saturated polymer rubber and polyester fiber,
Using an adhesive consisting of a nitrile group-containing highly saturated polymer rubber latex having an iodine value of 120 or less and a resorcinol-formaldehyde resin, drying, and then using a polyester fiber heat-treated at a temperature of 240 to 260 ° C. A featured bonding method is provided.

Hereinafter, the adhesive and the bonding method of the present invention and their characteristics will be described in detail.

As the nitrile group-containing highly saturated rubber constituting the latex of the present invention, a hydrogenated conjugated diene unit of an unsaturated nitrile-conjugated diene copolymer rubber; an unsaturated nitrile-conjugated diene-ethylenically unsaturated monomer-ternary copolymer Polymerized rubber and hydrogenated conjugated diene units of the rubber; unsaturated nitrile-ethylenically unsaturated monomer copolymer rubber. These nitrile group-containing highly saturated polymer rubbers can be obtained by using ordinary polymerization techniques and ordinary hydrogenation methods.

The monomers used for producing the nitrile group-containing highly saturated rubber of the present invention are exemplified below.

Examples of the unsaturated nitrile include acrylonitrile and methacrylonitrile, and examples of the conjugated diene include 1,3-butadiene, 2,3-dimethylbutadiene, isoprene, and 1,3-pentadiene. Examples of the ethylenically unsaturated monomer include acrylic acid, methacrylic acid, itaconic acid, unsaturated carboxylic acids such as maleic acid and salts thereof; methyl acrylate, ethyl acrylate, butyl acrylate,
Esters of the carboxylic acids such as 2-ethylhexyl acrylate, trifluoroethyl acrylate, tetrafluoropropyl acrylate; alkoxyalkyl esters of the unsaturated carboxylic acids such as methoxymethyl acrylate, ethoxyethyl acrylate, methoxyethoxyethyl acrylate; acrylamide; Methacrylamide; N-methylol (meth) acrylamide,
N-substituted (meth) acrylamides such as N, N'-dimethylol (meth) acrylamide and N-ethoxymethyl (meth) acrylamide; cyanomethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, 1-
Cyanopropyl (meth) acrylate, 2-ethyl-6
-Cyanohexyl (meth) acrylate, cyano-substituted alkyl (meth) acrylates such as 3-cyanopropyl acrylate, fluoroalkyl vinyl ethers such as fluoroethyl vinyl ether, vinyl pyridine and the like.

In the unsaturated nitrile-ethylenically unsaturated monomer copolymer rubber, a part of the unsaturated monomer is substituted with a non-conjugated diene such as vinyl norbornene, dicyclopentadiene, and 1,4-hexadiene. It may be copolymerized.

When the above monomers are copolymerized by a usual polymerization technique and a conjugated diene is frequently used, a nitrile group-containing compound is obtained by hydrogenating a conjugated diene unit in the obtained copolymer by a normal hydrogenation method. A highly saturated polymer rubber is produced.

Specific examples of the nitrile group-containing highly saturated rubber used in the present invention include hydrogenated butadiene-acrylonitrile copolymer rubber, isoprene-butadiene-acrylonitrile copolymer rubber, isoprene-acrylonitrile copolymer rubber; and butadiene. -Methyl acrylate-
Acrylonitrile copolymer rubber, butadiene-acrylic acid-acrylonitrile copolymer rubber, and hydrogenated products thereof; butadiene-ethylene-acrylonitrile copolymer rubber, butyl acrylate-ethoxyethyl acrylate-vinyl chloroacetate-acrylonitrile copolymer rubber, butyl acrylate -Ethoxyethyl acrylate-vinyl norbornene-acrylonitrile copolymer rubber.

The nitrile group-containing highly saturated polymer rubber latex of the present invention is produced by a known phase inversion method when the rubber is a hydrogenated rubber, and is produced by ordinary emulsion polymerization when the rubber is not a hydrogenated rubber.

Further, the polymer rubber constituting the nitrile group-containing highly-saturated polymer rubber latex has an iodine value of 120 determined according to JIS K 0070 in order to increase the bonding strength at the time of the above-mentioned vulcanization bonding and after the heat aging. Hereinafter, it is preferably in the range of 0 to 100. The content of the unsaturated nitrile unit in the polymer rubber can be arbitrarily selected according to the unit content of the adherend rubber (nitrile group-containing highly saturated polymer rubber) at the time of vulcanization and adhesion. It is in the range of 10 to 60% by weight in the polymer rubber.

Hereinafter, a method for producing the nitrile group-containing highly saturated polymer rubber latex of the present invention by a phase inversion method will be described as an example.

The phase inversion method is a method of mixing a solution of a nitrile group-containing highly saturated polymer rubber and an aqueous emulsifier solution, emulsifying and dispersing the polymer rubber as fine particles in water by vigorous stirring, and further removing the solvent. As a result, a latex of a nitrile group-containing highly saturated polymer rubber is obtained. As the nitrile group-containing highly saturated polymer rubber solution at that time, the solution at the end of the polymerization and the hydrogenation reaction can be used as it is, or a concentrated or diluted solution can be used, or the rubber in a solid state can be used as a solvent. It can be dissolved and used. Solvents such as aromatic solvents such as benzene, toluene and xylene, halogenated hydrocarbon solvents such as dichloroethane and chloroform, and ketones such as methyl ethyl ketone, acetone and tetrahydrofuran which are soluble in the polymer rubber are used alone or as a mixture. Used. The concentration of the nitrile group-containing highly saturated polymer rubber in the solution is usually in the range of 1 to 25% by weight. Emulsifiers include oleic acid, fatty acids such as stearic acid, rosin acid, alkylbenzene sulfonic acid,
Potassium salts such as alkyl sulfates, sodium salts, polyoxyethylene nonionic emulsifiers, etc.
Used alone or as a mixture.

The volume ratio of the nitrile group-containing highly saturated polymer rubber solution to water is usually in the range of 3: 1 to 1:20. Various homomixers, ultrasonic emulsifiers, and the like are used as a stirrer for emulsification and dispersion. The removal of the solvent from the emulsion is performed by a known method such as a steam stripping method.

The adhesive for vulcanizing and bonding the nitrile group-containing highly saturated polymer rubber and the polyester fiber of the present invention is obtained by blending a resorcinol-formaldehyde resin with the above nitrile group-containing highly saturated polymer rubber latex. Conventional resins (for example, those disclosed in JP-A-55-142635) can be used, and there is no particular limitation.

Also, conventionally used to increase the adhesive strength2,
6-bis (2,4-dihydroxyphenylmethyl) -4-chlorophenol (for example, trade name Vulcabond E, manufactured by Barnax), 2,6-bis (2,4-dihydroxyphenylmethyl) -4-bromophenol, A combined use with a phenol compound such as 2,6-bis (2,4-dichlorophenylmethyl) -4-chlorophenol and a polyhydric phenol polysulfide compound is also acceptable.

The adhesive of the present invention is usually one obtained by mixing 10 to 180 parts by weight (dry weight) of a resorcin-formaldehyde resin with respect to 100 parts by weight of the solid content of the polymer rubber latex of the present invention.

When a phenol compound is used in combination, a mixture of 20 to 100 parts by weight (dry weight) of the phenol compound with respect to 100 parts by weight of the solid content of the polymer rubber latex of the present invention is used. The adhesive using the phenol compound may be used in a complex treatment in which the polyester rubber alone or the adhesive using the phenol compound is attached to the polyester fiber, and then the polymer rubber latex-resorcin-formaldehyde resin is attached.

Also, a part of the rubber latex of the present invention in the adhesive of the present invention is a styrene-butadiene copolymer rubber latex and its modified latex, an acrylonitrile-butadiene copolymer rubber latex and its modified as long as the gist of the present invention is not impaired. Latex, natural rubber latex, etc. can be replaced by one or more of them.

The adhesion of the adhesive to the fibers is generally performed by a dipping method, but other methods may be used. Usually, the adhesive amount is 5 to the fiber.
The dipping time, the solid content of the adhesive, and the like are adjusted so as to be 6% by weight. The fibers to which the adhesive has been adhered are dried at a temperature of 100 to 150 ° C. for about 0.5 to 10 minutes.

Subsequently, heat treatment is performed, and the heat treatment is performed at a temperature of 240 to 260 ° C., which is a feature of the present invention. This heat treatment is usually 0.5
It is performed for about 3 minutes, and the adhesive cures. The heat treatment at a temperature lower than 240 ° C. does not improve the initial adhesive strength between the polymer rubber of the present invention and the adhesive. Not a target. Preferably it is 245 to 260 ° C.

As the polyester fiber used in the present invention, a polyester fiber conventionally used as a reinforcing fiber can be used and is not particularly limited. Polyester fibers are used in the form of staples, filaments, cords, ropes, canvas and the like.

The nitrile group-containing polyvalent saturated polymer rubber which is the adherend of the polyester fiber used in the present invention is a monomer unit in the nitrile group-containing highly saturated polymer rubber and the rubber constituting the latex of the present invention, The same, the content of the unsaturated nitrile unit is usually in the range of 10 to 60% by weight from the viewpoint of oil resistance of the rubber product compounded with the fiber, and the iodine value is preferably 120 or less from the viewpoint of heat resistance, preferably 0-100, more preferably 0
It is in the range of 80.

The bonding between the rubber and the fiber using the adhesive of the present invention is prepared by adding a compounding agent such as a vulcanizing agent or a filler to the fiber and the rubber that have been subjected to a dipping treatment and then a heat treatment with the adhesive of the present invention. It is achieved by vulcanizing after having a composite value with the obtained rubber compound.

Usually, prior to immersion in the treatment station, the fibers can be immersed in an isocyanate solution, an epoxy solution, or a mixed solution thereof and dried.

(Effect of the Invention) The nitrile group-containing highly saturated polymer rubber latex of the present invention is mixed with a resorcinol-formaldehyde resin to form an adhesive for vulcanization bonding between rubber and polyester fiber, and the nitrile group-containing highly saturated polymer rubber is produced. When used for vulcanization bonding with the fiber, gives excellent initial adhesive strength as compared with the conventional adhesive, and extremely remarkable adhesive strength after heat aging as compared with the case where the conventional adhesive is used. Thus, it can be used for the production of various belts such as toothed conductive belts and V-belts using organic synthetic fibers as tensile members, and various hoses such as pressure-resistant hoses and freon hoses.

(Example) Hereinafter, the present invention will be described more specifically with reference to examples. Parts and% in Examples and Comparative Examples are based on weight unless otherwise specified.

Examples 1 to 10 and Comparative Examples 1 to 6 Emulsion-polymerized acrylonitrile-butadiene copolymer rubber (NBR, amount of bound acrylonitrile 37% by weight) was dissolved in methyl isobutyl ketone, and the butadiene portion in NBR was dissolved using a palladium-carbon catalyst. 60 g of hydrogenated NBR (iodine value 80) obtained by hydrogenation was dissolved in 540 g of a mixed solvent of methyl ethyl ketone / cyclohexane (50/50% by volume).

While stirring with a homomixer (M type manufactured by Tokushu Kika Kogyo Co., Ltd.), 32 g of a 15% aqueous solution of potassium oleate adjusted to pH 11.5 with potassium hydroxide and 600 g of water were added to the rubber solution. For 10 minutes to emulsify.

The solvent was removed from the resulting emulsion by steam stripping, and then concentrated using an evaporator to obtain a latex having a solid content of about 30%. 10 at room temperature
Centrifugation at 000 rpm for 16 minutes (H25 made by domestic centrifuge)
By subjecting it to 1), a latex (A) having a solid content of 40% was obtained.

Similarly, a latex (B) of hydrogenated NBR having an iodine value of 28 (Zetpol2020 manufactured by Zeon Corporation, bound acrylonitrile amount: 37%) having a solid content of about 30% was prepared.

For comparison, an NBR latex having a solid content of about 30% (iodine value of NBR: 248, bound acrylonitrile amount: 37%) was prepared by emulsion polymerization.

(Preparation of rubber compound to be adhered) According to the compounding recipe shown in Table 1, the nitrile group-containing highly saturated polymer rubber and the compounding agent were kneaded on a roll, and the mixture was mixed to about 2.5 mm
A sheet of a rubber compound having a thickness of 1 mm was prepared.

(Preparation of RFL solution) According to the formulations in Tables 2 and 3, the nitrile group-containing highly saturated polymer rubber (hydrogenated NBR) latex (A) and (B) and the NBR latex were used to prepare the RFL solution (adhesion). Agent) was prepared.

A polyester fiber cord (polyethylene terephthalate, structure 1500d / 2) was immersed in the first bath RFL solution shown in Table 2 and 14
After drying at 0 ° C. for 45 seconds and heat treatment, it was then immersed in the RFL solution of the second bath shown in Table 3, dried at 140 ° C. for 45 seconds, and heat treated. The heat treatment temperature after immersion in the first and second baths is the same, and is the temperature described in Table 4. The treated cord was sandwiched between the rubber compositions to be adhered as shown in Table 1 and subjected to a cord peeling test (ASTMD-2630).
(According to -71). The test specimen is 30
Vulcanized for minutes. The test pieces were subjected to an air heat aging test at 120 ° C. for 7 days in order to check the cord peel strength after aging. Table 4 shows the results of the initial adhesive strength and the adhesive strength after heat aging.

Similar to the conventional heat treatment of the rubber and the polyester fiber after the adhesion of the adhesive in the vulcanization adhesion of the polyester fiber, the vulcanization adhesion of the rubber of the present invention and the fiber to which the adhesive of the present invention is adhered is also performed by the conventional heat treatment. Within the range of the temperature, the initial adhesive strength is slightly improved with the heat treatment temperature (Comparative Examples 1 to 5).
4).

However, surprisingly, it can be seen from the results of Table 4 that the initial adhesive strength is remarkably improved at the heat treatment temperature of the present invention, especially at 245 ° C. or higher.

Claims (1)

(57) [Claims] An adhesive comprising a nitrile group-containing highly saturated polymer rubber latex having an iodine value of 120 or less and a resorcinol-formaldehyde resin when vulcanizing and bonding a nitrile group-containing highly saturated polymer rubber to polyester fiber. A bonding method characterized by using polyester fibers which are heat-treated at a temperature of 240 to 260 ° C. after being attached and dried.